Cooling apparatus having an auxiliary chiller, and an apparatus and method of fabricating a semiconductor device using the same

ABSTRACT

A cooling apparatus having an auxiliary chiller is provided. The apparatus can include a wafer chuck on which a wafer is mounted and in which a cooling cavity is formed. A main chiller having a main coolant reservoir can be spaced apart from the wafer chuck. The cooling cavity and the main coolant reservoir can be arranged in communication with each other through coolant passages. The coolant passages can include an auxiliary chiller detachably installed thereon, respectively. A method of cooling a wafer chuck or process chamber during a semiconductor device fabrication process is also provided. Using the method and apparatuses of this invention, fine temperature adjustments of the wafer chuck are possible.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No. 2006-78231, filed Aug. 18, 2006, the contents of which are hereby incorporated herein by reference in their entirety.

BACKGROUND

1. Field of the Invention

The present invention relates to an apparatus and method of fabricating a semiconductor device, and more particularly, to a cooling apparatus having an auxiliary chiller, and an apparatus and method of fabricating a semiconductor device using the cooling apparatus.

2. Description of Related Art

A semiconductor device generally includes a plurality of electric circuits. The circuits are formed on a semiconductor substrate using a photolithography process. The photolithography process may include etching and patterning a conductive layer deposited on the substrate by a vapor deposition process, thus forming the circuits.

The vapor deposition process and the etching process are performed in their own respective process chamber. A wafer chuck fixes a wafer during the vapor deposition process and the etching process.

Various plasma deposition and etching apparatuses are now widely used to form and etch layers on a wafer. In conventional plasma processing apparatuses, the wafer chuck is used as an electrode for forming plasma from a gas injected into the chamber. Therefore, when the plasma process is performed, the temperature of the wafer chuck increases due to the hot plasma formed in the chamber. Temperature characteristics of the wafer supported by the wafer chuck are directly affected by temperature fluctuations of the wafer chuck. These fluctuations cause a variation in an etch rate, thereby contributing to non-uniformities of the layer's critical dimensions and line widths.

To improve thermal conditions, a chiller is used to equalize the temperature of the wafer chuck.

FIG. 1 is a schematic view of a conventional apparatus for fabricating a semiconductor device 200. The conventional apparatus includes a chiller 14. The apparatus 200 includes a wafer chuck 12 disposed in a process chamber 10. The wafer chuck 12 fixes a wafer W to its upper surface. The wafer chuck 12 may be heated to a high temperature during a semiconductor device fabrication process.

The semiconductor device fabrication apparatus includes a chiller 14 for equalizing the temperature of the wafer chuck 12. In addition, the wafer chuck 12 has a cooling passage 16 formed therein. The chiller 14 includes a first heat exchanger 18 spaced apart from the cooling passage 16. The cooling passage 16 and the first heat exchanger 18 are connected to each other through a coolant supply passage 20 a and a coolant collecting passage 20 b. Therefore, the coolant cooled by the first heat exchanger 18 may be supplied into the cooling passage 16 through the coolant supply passage 20 a, thereby cooling the high temperature wafer chuck 12 using the coolant supplied into the cooling passage 16.

Consequently, the coolant, after cooling the high temperature wafer chuck 12, is heated to a high temperature through heat exchange with the wafer chuck 12. The high temperature coolant is collected into the first heat exchanger 18 through the coolant collecting passage 20 b. The coolant collected into the first heat exchanger 18 is cooled by the first heat exchanger 18. In this way, the coolant supplied into the cooling passage 16 of the wafer chuck 12 circulates through the first heat exchanger 18 and the wafer chuck 12.

Meanwhile, the chiller 14 includes a second heat exchanger 22 spaced apart from the first heat exchanger 18. The first and second heat exchangers 18 and 22 are in communication with each other through a compressor 24 disposed therebetween. As a result, a cooling medium in the first heat exchanger 18 can be provided into the second heat exchanger 22 through the compressor 24. Conventionally, the cooling medium may be Freon gas.

In addition, the first and second heat exchangers 18 and 22 are also installed in communication with each other through an expansion valve 26 disposed therebetween. Therefore, the cooling medium in the second heat exchanger 22 can also be provided into the first heat exchanger 18 through the expansion valve 26.

As a result, the cooling medium can circulate by sequentially passing through the first heat exchanger 18, the compressor 24, the second heat exchanger 22, and the expansion valve 26, back to the first heat exchanger 18. That is, the cooling medium can be compressed by the compressor 24, providing the compressed cooling medium into the second heat exchanger 22. The cooling medium provided into the second heat exchanger 22 can be condensed by cooling water passing through the second heat exchanger 22. The condensed cooling medium is supplied into the expansion valve 26, and the cooling medium supplied into the expansion valve 26 can be expanded. The expanded cooling medium then can be provided into the first heat exchanger 18 from the wafer chuck 12. The cooling medium provided into the first heat exchanger 18 is heated to a high temperature by the high temperature coolant passing through the first heat exchanger 18. The high temperature cooling medium is then provided back into the compressor 24, thereby completing one cooling cycle.

By repeatedly performing the cooling cycle, the coolant passing through the first heat exchanger 18 can be cooled. Therefore, a cooling efficiency of the coolant can be determined by the number of cooling cycles, an amount of the cooling medium circulated from the first heat exchanger to the expansion valve, a temperature difference between the coolant and the cooling medium, and so on.

In contrast to the general fabrication process described above, recent semiconductor device fabrication practice may now include different processes performed using a single process chamber. For example, the etching process and the deposition process can be performed in situ using the same chamber. In this case, the wafer chuck should be maintained at a temperature appropriate to each process. That is, the temperature of the wafer chuck should be controlled and modifies in response to the different processes. Therefore, the temperature of the coolant passing through the wafer chuck should be carefully controlled and finely adjusted. For example, it is necessary to carefully and precisely lower the temperature of the coolant using a chiller system having a certain cooling capacity related to a corresponding temperature. And the temperature of the cooling medium provided into the first heat exchanger should be precisely lowered after performing one cooling cycle.

However, in conventional chiller systems, since an amount of the cooling medium is measured specifically for each chiller system, it is difficult to adjust the temperature of the coolant by varying the amount of cooling medium. In addition, since the temperature of the cooling medium varies greatly, it is difficult to precisely adjust the temperature of the cooling medium by increasing the number of cooling cycles.

Meanwhile, if the conventional chiller were to be replaced with a chiller having a more finely adjusted cooling capacity, then manufacturing costs would increase, along with an increased process time for manufacturing the semiconductor device.

Therefore, it is desirable to provide an apparatus for precisely adjusting the temperature of the wafer chuck using the conventional chiller system of the apparatus for fabricating a semiconductor device.

SUMMARY

In one embodiment of the invention a cooling apparatus has an auxiliary chiller. In another embodiment of the invention an apparatus for fabricating a semiconductor device has an auxiliary chiller detachably installed at a main chiller. In still another embodiment of the invention a method of fabricating a semiconductor device includes precisely and finely adjusting the temperature of a coolant.

In one aspect, the invention is directed to a cooling apparatus having an auxiliary chiller. The apparatus includes a wafer chuck which is used to fix a wafer having a cooling cavity formed therein. A main chiller having a main coolant cavity may be spaced apart from the wafer chuck. The cooling cavity and the main coolant cavity communicate with each other through coolant passages. The coolant passages include a detachably installed auxiliary chiller.

In some embodiments of the present invention, the coolant passages may include a first coolant supply line connected to the auxiliary chiller and a first coolant collecting line.

In another embodiment, the apparatus may further include first and second coupling parts disposed along the first coolant supply line connected to the auxiliary chiller. In this case, the first and second coupling parts may have coupling lines connected to the first coolant supply line. A first switching valve and coupling nuts may be installed along the coupling lines. A second switching valve installed on the first coolant supply line is disposed between the first and second coupling parts.

In still another embodiment, the apparatus may include a temperature sensor adapted to sense the cooling cavity temperature. The apparatus may include a controller electrically connected to the temperature sensor, and to the first and second switching valves. In this case, the controller may operate the first and second switching valves in response to a temperature value transmitted to the controller from the temperature sensor.

In yet another embodiment, the auxiliary chiller may include an auxiliary coolant cavity. The auxiliary chiller may include second auxiliary coolant supply lines connected to the first and second coupling parts and extending from the auxiliary coolant cavity. First conductors may be disposed adjacent to the auxiliary coolant cavity. Second conductors may be spaced apart from the first conductors. The auxiliary chiller may include first semiconductors disposed between the first and second conductors and electrically connecting the first and second conductors. The auxiliary chiller may include a first power source connected to the second conductors.

In yet another embodiment, the apparatus may further include a cooling water circulation passage disposed adjacent to the second conductors. The apparatus may further include a cooling water supply cavity arranged in communication with the cooling water circulation passage.

In yet another embodiment, the apparatus may further include heat radiation fins disposed adjacent to the second conductors.

In yet another embodiment, the apparatus may further include a coolant heater installed along the first coolant collecting line.

In yet another embodiment, the main chiller may include a first heat exchanger disposed adjacent to the main coolant cavity. First and second cooling medium passages may be connected to the first heat exchanger. The main chiller may include a second heat exchanger in communication with the first heat exchanger through the first and second cooling medium passages. A compressor may be installed on the first cooling medium passage between the first and second heat exchangers. Expansion valves may be disposed on the second cooling medium passages between the first and second heat exchangers.

In yet another embodiment, the main chiller may include third conductors disposed adjacent to the main coolant cavity. The main chiller may include fourth conductors spaced apart from the third conductors. The main chiller may include second semiconductors disposed between the third and fourth conductors and electrically connecting the third and fourth conductors. The main chiller may include a second power source applied to the fourth conductors.

In another aspect, the invention is directed to an apparatus for cooling a wafer chuck during fabrication of a semiconductor device having an auxiliary chiller detachably installed in communication with the main chiller. The apparatus includes a process chamber A process gas introduction port is arranged communication with the process chamber. The apparatus includes a wafer chuck disposed in the process chamber and having a cooling cavity formed therein. The apparatus may include a coolant supply line for connecting the cooling cavity and the main chiller. An auxiliary chiller is detachably installed on the coolant supply line. A process gas exhaust port is arranged in communication with the process chamber. A first power source is electrically connected to the process chamber.

In some embodiments of the present invention, the apparatus may further include first and second coupling parts disposed along the coolant supply line. The apparatus may further include a first switching valve disposed between the first and second coupling parts and installed on the coolant supply line. The auxiliary chiller may be connected to the first and second coupling parts.

In another embodiment, the first and second coupling parts may include coupling lines connected to the coolant supply line, and second switching valves and coupling nuts along the coupling lines.

In still another embodiment, the apparatus may further include a temperature sensor adapted to sensing the cooling cavity temperature. The apparatus may further include a controller electrically connected to the temperature sensor, and to the first and second switching valves. In this case, the controller may operate the first and second switching valves in response to a temperature value transmitted from the temperature sensor to the controller.

In yet another embodiment, the auxiliary chiller may include an auxiliary coolant cavity connected to the first and second coupling parts. First conductors may be disposed adjacent to the auxiliary coolant cavity. Second conductors may be spaced apart from the first conductors. The auxiliary chiller may include first semiconductors disposed between the first and second conductors and electrically connecting the first and second conductors. The auxiliary chiller may include a second power source connected to the second conductors.

In yet another embodiment, the apparatus may further include a cooling water circulation passage disposed adjacent to the second conductors. The apparatus may further include a cooling water supply cavity arranged in communication with the cooling water circulation passage.

In yet another embodiment, the apparatus may further include heat radiation fins disposed adjacent to the second conductors.

In yet another embodiment, the apparatus may further include a coolant heater installed along the coolant collecting line.

In yet another embodiment, the main chiller may include a first main coolant reservoir connected to the coolant supply line and the coolant collecting line. The main chiller may include a first heat exchanger disposed adjacent to the first main coolant reservoir. First and second cooling medium passages may be connected to the first heat exchanger. The apparatus may include a second heat exchanger arranged in communication with the first heat exchanger through the first and second cooling medium passages. A compressor may be installed on the first cooling medium passage between the first and second heat exchangers. The main chiller may include expansion valves installed along the second cooling medium passage between the first and second heat exchangers.

In yet another embodiment, the main chiller may include a second main coolant reservoir connected to the coolant supply line and the coolant collecting line. Third conductors may be disposed adjacent to the second main coolant reservoir. Fourth conductors may be spaced apart from the third conductors. The main chiller may include second semiconductors disposed between the third and fourth conductors and electrically connecting the third and fourth conductors. The main chiller may include a third power source connected to the fourth conductors.

In still another aspect, the present invention is directed to a method of precisely and finely controlling the temperature of a wafer chuck used to fabricating a semiconductor device. The method includes setting a control temperature for a coolant. The coolant cooled by the main chiller is supplied to the wafer chuck. A temperature of the coolant supplied to the wafer chuck is measured. The measured temperature of the coolant is compared with the set temperature. When the measured temperature is higher than the control temperature, supply of the cooled coolant to the wafer chuck may be stopped or altered. The coolant cooled by the main chiller is then supplied to an auxiliary chiller. The coolant supplied to the auxiliary chiller is additionally cooled. The additionally cooled coolant is then supplied to the wafer chuck.

In some embodiments of the present invention, the method may further include collecting the coolant supplied to the wafer chuck before cooling the coolant in the main chiller. The method may further include heating the collected coolant.

In another embodiment, the coolant supplied to the auxiliary chiller may be additionally cooled by a thermo-electric cooler.

In still another embodiment, the coolant in the main chiller may be cooled by a mechanical cooler including a compressor for compressing cooling medium, a condenser for condensing the compressed cooling medium, an expansion valve for expanding the condensed cooling medium, and an evaporator for evaporating the expanded cooling medium.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of the invention will be apparent from the more particular description of preferred embodiments, as illustrated in the accompanying drawing. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

FIG. 1 is a schematic block diagram of a conventional apparatus for fabricating a semiconductor device, where the apparatus includes a chiller.

FIG. 2 is a schematic block diagram of a semiconductor device fabricating apparatus including a cooling apparatus, constructed in accordance with an exemplary embodiment.

FIG. 3 is a schematic cross-sectional side view of an auxiliary chiller of the cooling apparatus of FIG. 2 in accordance with another aspect of the invention.

FIG. 4 is an exploded perspective view of the auxiliary chiller of FIG. 3.

FIG. 5 is a perspective view of the auxiliary chiller of FIGS. 3 and 4.

FIG. 6 is a schematic cross-sectional side view of an auxiliary chiller of the cooling apparatus of FIG. 2 in accordance with another exemplary embodiment.

FIG. 7 is a schematic block diagram of a main chiller of the cooling apparatus of FIG. 2 in accordance with an exemplary embodiment.

FIG. 8 is a schematic cross-sectional side view of a main chiller of the cooling apparatus of FIG. 2 in accordance with another exemplary embodiment.

FIG. 9 is a flowchart illustrating a method of cooling a wafer chuck during fabrication of a semiconductor device in accordance with another exemplary embodiment.

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. This invention may, however, be embodied in different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the length and thickness of layers and regions may be exaggerated for clarity. Like reference numerals designate like elements throughout the specification and drawings.

FIG. 2 is a schematic view of a cooling apparatus 300 and an apparatus for fabricating a semiconductor device 200 including the same in accordance with an exemplary embodiment. FIG. 3 is a schematic view of an auxiliary chiller 84 of the cooling apparatus 300 of FIG. 2 in accordance with an exemplary embodiment. FIG. 4 is an exploded perspective view of the auxiliary chiller 84 of FIG. 3. FIG. 5 is a perspective view of the auxiliary chiller 84 of FIGS. 3 and 4. FIG. 6 is a schematic view of an auxiliary chiller 84 a of the cooling apparatus 300 of FIG. 2 in accordance with another exemplary embodiment. FIG. 7 is a schematic view of a main chiller 30 of the cooling apparatus 300 of FIG. 2 in accordance with yet another exemplary embodiment. FIG. 8 is a schematic view of a main chiller 30 of the cooling apparatus 300 of FIG. 2 in accordance with another exemplary embodiment. And FIG. 9 is a flowchart illustrating a method of cooling a wafer chuck 12 during fabrication of a semiconductor device in accordance with a further exemplary embodiment.

Referring to FIG. 2, the cooling apparatus 300 in accordance with an embodiment of the invention includes a main chiller 30. The main chiller 30 may be used to cool a wafer chuck 32, which is used for fixing a wafer W in a process chamber 34. However, the main chiller 30 may also be used to cool the process chamber 34 for fabricating a semiconductor device.

The wafer chuck 32 is disposed in the process chamber 34. The process chamber 34 may be adapted to provide a plasma processing apparatus. In this case, the wafer chuck 32 may function as a lower electrode. In addition, an upper electrode 36 may be disposed over the wafer chuck 32. A process gas supply passage 38 may be disposed over the upper electrode 36 to supply a process gas to the process chamber 34. The process gas supply passage 38 may be in communication with a process gas supply 40. In addition, the process gas supply passage 38 may be in communication with a process gas introduction port 42 disposed at the process chamber 34. A valve 46 installed on the process gas supply passage 38 may permit adjustment of the supply of the process gas. The valve 46 may, for instance include a switching valve or a solenoid valve.

The process chamber 34 may also be in communication with a process gas exhaust passage 48 through a process gas discharge port 50 disposed in the process chamber 34. In addition, a pump 52 installed on the process gas exhaust passage 48 may pump the process gas in the process chamber 34.

A high-frequency power source 54 spaced apart from the process chamber 34 may be electrically connected to the wafer chuck 32. Therefore, when the high-frequency power source is applied to the wafer chuck 32, plasma may be generated from the gas introduced to the process chamber 34. Therefore, when a plasma treatment process is performed, the wafer chuck in the process chamber 34 heats up to a high temperature due to the hot plasma in the process chamber 34. Then, to maintain the wafer chuck 34 at a uniform temperature, a chiller system 300 cools the wafer chuck 32.

The chiller system 300 includes the main chiller 30. The main chiller 30 is arranged in communication with the wafer chuck 32. A cooling cavity 56 may be formed in the wafer chuck 32. The cooling cavity 56 may be a plurality of spiral coolant passages filled with a coolant. In addition, the main chiller 30 may include a main coolant reservoir 58. The main coolant reservoir 58 may also be filled with a coolant. The main chiller 30 may cool the coolant in the main coolant reservoir 58. Therefore, the coolant cooled by the main chiller 30 may be supplied to the cooling cavity 56 of the wafer chuck 32.

The coolant in the cooling cavity 56 and the main coolant reservoir 58 may be a cooling medium having a high specific heat, a high thermal conductivity, low viscosity, and high insulating characteristics. The coolant may be ethylene glycol or propylene glycol, for example.

The cooling cavity 56 and the main chiller 30 may be connected by a coolant supply line 60 a and a coolant collecting line 60 b disposed therebetween. The coolant supply line 60 a and the coolant collecting line 60 b may be filled with a coolant. The coolant cooled in the main chiller 30 can be supplied to the cooling cavity 56 through the coolant supply line 60 a. The wafer chuck 32 may be cooled by the coolant provided to the cooling cavity 56. As a result, the coolant discharged from the cooling cavity 56 may be a high temperature coolant. Then, the high temperature coolant discharged from the cooling cavity 56 may be collected to the main coolant reservoir 58 of the main chiller 30 through the coolant collecting line 60 b. The coolant may repeatedly circulate by sequentially passing through the main chiller 30, the coolant supply line 60 a, the cooling cavity 56, and the coolant collecting line 60 b. In order to circulate the coolant, a pump 62 may be disposed in the coolant supply line 60 a.

In addition, a valve 64 may be installed on the coolant supply line 60 a. The valve 64 can be used to adjust an amount of the coolant supplied to the cooling cavity 56 through the coolant supply line 60 a. The valve 64 may, for example, include a switching valve or a solenoid valve, as one skilled in the art would realize.

In addition, a temperature sensor 66 may be electrically connected to the coolant supply line 60 a. The temperature sensor 66 can sense the temperature of the coolant in the coolant supply line 60 a that is being provided to the cooling cavity 56. In addition, a temperature sensor 68 may be electrically connected to the coolant collecting line 60 b. The temperature sensor 68 can sense the temperature of the coolant in the coolant collecting line 60 b discharged from the cooling cavity 56. In addition, the cooling apparatus 300 in accordance with the present embodiment may include a temperature sensor 70 electrically connected to the cooling cavity 56. The temperature sensor 70 can sense the temperature of the coolant in the cooling cavity 56.

In addition, a coolant heater 72 may be installed on the coolant collecting line 60 b. The coolant heater 72 may include a power source 74 and a coil surrounding the coolant collecting line 60 b. In this case, the coil may be electrically connected to the power source 74. Therefore, a predetermined voltage may be applied from the power source 74 to the coil to heat the coolant in the coolant collecting line 60 b. Since the predetermined voltage may be adjusted by a controller 76 electrically connected to the power source 74, the coolant may be variably heated.

The cooling apparatus in accordance with the present embodiment may include first and second coupling lines 78 a and 78 b that diverge from the coolant supply line 60 a. The first and second coupling lines 78 a and 78 b may be spaced apart from each other. In this case, the valve 64 installed on the coolant supply line 60 a may be disposed between the diverging positions at which the first and second coupling lines 78 a and 78 b are disposed, respectively. The coolant supply line 60 a may be in communication with the first and second coupling lines 78 a and 78 b. The coupling lines 78 a and 78 b may include valves 80 a and 80 b and coupling nuts 82 a and 82 b disposed at their ends. The valves 80 a and 80 b may include switching valves and solenoid valves. The switching valves can open and close the first and second coupling lines 78 a and 78 b to control the flow of the coolant. In addition, the solenoid valves can adjust an amount of the coolant flowing through the first and second coupling lines 78 a and 78 b. Further, the coupling nuts 82 a and 82 b may be engaged with male threads formed on outer peripheries of the coupling lines 78 a and 78 b.

In addition, the first and second coupling lines 78 a and 78 b are in communication with an auxiliary chiller 84 disposed therebetween. The auxiliary chiller 84 may include an auxiliary coolant reservoir 86. In addition, a first auxiliary line 88 a is connected to a first end of the auxiliary coolant reservoir 86. Similarly, a second auxiliary line 88 b is connected to a second end of the auxiliary coolant reservoir 86 opposite to the first end.

The first and second auxiliary lines 88 a and 88 b may have male threads formed on outer peripheries of their ends. Therefore, the first auxiliary line 88 a may be engaged with the first coupling line 78 a by the coupling nut 82 a of the first coupling line 78 a. Similarly, the second auxiliary line 88 b may be engaged with the second coupling line 78 b by the coupling nut 82 b of the second coupling line 78 b. In addition, by releasing the coupling nuts 82 a and 82 b, it is possible to separate the first and second auxiliary lines 88 a and 88 b from the first and second coupling lines 78 a and 78 b, respectively. As a result, the auxiliary chiller 84 may be detachably installed on the first and second coupling lines 78 a and 78 b.

Meanwhile, when the auxiliary chiller 84 is fastened to the first and second coupling lines 78 a and 78 b so that the coolant in the coolant supply line 60 a is provided to the auxiliary chiller 84, it is possible to adjust the valve 64 of the coolant supply line 60 a to thereby adjust an amount of the coolant passing through the coolant supply line 60 a. In this case, the coolant in the coolant supply line 60 a may be supplied to the auxiliary chiller 84 through the first coupling line 78 a. The auxiliary chiller 84 may cool the coolant supplied to the auxiliary chiller 84. Therefore, the coolant cooled by the main chiller 30 may be additionally cooled by the auxiliary chiller 84. The additionally cooled coolant may be supplied to the cooling cavity 56 of the wafer chuck 32 by sequentially passing through the second auxiliary line 88 b, the second coupling line 78 b, and the coolant supply line 60 a. Therefore, when it is necessary to additionally cool the coolant cooled by the main chiller 30, the auxiliary chiller 84 may be installed at the main chiller 30.

An intensity of the additional cooling may be determined by the cooling capacity of the auxiliary chiller 84. In addition, by adjusting the valve 64 of the coolant supply line 60 a and the valves 80 a and 80 b of the first and second coupling lines 78 a and 78 b, an amount of the coolant supplied to the auxiliary chiller 84 can be adjusted. That is, it is possible to adjust the intensity of the additional cooling by adjusting an amount of the coolant supplied to the auxiliary chiller 84. Therefore, it is possible to control the temperature of the coolant supplied to the cooling cavity 56 of the wafer chuck 32. In this case, the valves 64, 80 a and 80 b, a variable power supply of the pump 62, and the temperature sensors 66, 68 and 70 may be electrically connected to the controller 76. The controller 76 may include a PID (proportional integral derivatives) program installed therein. In addition, a predetermined temperature value of the coolant may be set in the controller 76. Therefore, when the valves 64, 80 a and 80 b are solenoid valves and the temperature of the coolant in the cooling cavity 56 is higher than the predetermined temperature of the coolant, the valve 64 of the coolant supply line 60 a may be closed and the valves 80 a and 80 b of the first and second coupling lines 78 a and 78 b may be opened. Therefore, it is possible to automatically lower the temperature of the coolant supplied to the cooling cavity 56 by an additional amount.

Hereinafter, an auxiliary chiller 84 in accordance with one embodiment will be described in greater detail.

Referring to FIGS. 2 to 5, the auxiliary chiller 84 may employ a thermo-electric cooler. When the auxiliary chiller 84 includes the thermo-electric cooler, it may include first conductors 90 a disposed adjacent to the auxiliary coolant reservoir 86. In addition, second conductors 90 b may be disposed spaced apart from the first conductors 90 a. The first and second conductors 90 a and 90 b may have a plate shape. In this case, each of the first conductors 90 a may be spaced apart from each other. Similarly, each of the second conductors 90 b may also be spaced apart from each other. In this way, each of the spaced apart first and second conductors 90 a and 90 b may be positioned alternately with respect to each other. An example of this configuration is shown in FIG. 3. The first and second conductors 90 a and 90 b may have high conductivity, being made of aluminum or copper, for example.

Semiconductors 92 a and 92 b may be disposed between the first and second conductors 90 a and 90 b, as shown in the embodiment of FIG. 3. The semiconductors 92 a and 92 b may comprise a plurality of semiconductor pairs. In this case, the pair of semiconductors 92 a and 92 b may have different conductivity types. For example, one of the semiconductors in the pair may be N-type, while the other semiconductor may be P-type.

The semiconductors 92 a and 92 b may be electrically connected to each other by the first and second conductors 90 a and 90 b. Specifically, ends of each semiconductor pair 92 a and 92 b may be electrically connected to each other by the first conductors 90 a, with ends of other semiconductor pairs 92 a and 92 b adjacent to each other being connected by the second conductors 90 b. That is, the first and second semiconductors 92 a and 92 b may be electrically connected to each other serially using the first and second conductors 90 a and 90 b, alternately.

A power source 94 may be electrically connected to the second conductors 90 b arranged as described above. The Peltier effect may occur when a voltage is applied from the power source 94 to the second conductors 90 b and an electric current flows through the second conductors 90 b, the semiconductors 92 b, the first conductors 90 a, and the semiconductors 92 a. The Peltier effect will heat the first conductors 90 a and cool the second conductors 90 b, or vice versa. Therefore, the first conductors 90 a may function as heat absorption plates, and the second conductors 90 b may function as heat radiation plates.

As a result, when the auxiliary coolant reservoir 86 is disposed adjacent to the first conductors 90 a, the coolant in the auxiliary coolant reservoir 86 may be cooled by the first conductors 90 a. In this case, the auxiliary cooling reservoir 86 disposed adjacent to the first conductors 90 a may be disposed on upper surfaces of the conductors 90 a in a zigzag manner for the sake of increased efficiency.

As described above, since the coolant in the auxiliary coolant reservoir 86 can be cooled by the first conductors 90 a, it is possible to finely adjust the temperature of the coolant in the auxiliary coolant reservoir 86. For example, by adjusting a voltage apnlied to the second conductors 90 b, it is possible to precisely adjust the intensity of the additional cooling by the first conductors 90 b. In addition, an electrical insulating heat conductor 96 may be disposed between the auxiliary cooling reservoir 86 and the first conductors 90 a. The electrical insulating heat conductor 96 may be an electrical insulator containing amorphous diamond or ceramic.

Further, the second conductors 90 b functioning as the heat radiation plates may be cooled using a water cooler. That is, a cooling water circulation passage 98 may be disposed adjacent to the second conductors 90 b. An electrical insulating heat conductor 100 may be interposed between the second conductors 90 b and the cooling water circulation passage 98. The cooling water circulation passage 98 may communicate with a cooling water supply reservoir 106 through a cooling water supply passage 102 and a cooling water collecting passage 104. A pump 108 may be installed along the cooling water supply passage 102. The cooling water in the cooling water supply reservoir 106 can thereby be supplied to the cooling water circulation passage 98 through the cooling water supply passage 102. The cooling water supplied to the cooling water circulation passage 98 can cool the second conductors 90 b. In this case, the cooling water supplied to the cooling water circulation passage 98 may be heated to a high temperature after exchanging heat with the second conductors 90 b. The high temperature cooling water may be collected to the cooling water supply reservoir 106 through the cooling water collecting passage 104. The cooling water supply reservoir 106 may cool the cooling water collected to the cooling water supply reservoir 106. The cooling water may circulate by sequentially passing through the cooling water supply passage 102, the cooling water circulation passage 98, the cooling water collecting passage 104, and the cooling water supply reservoir 106.

In addition, the cooling water supply passage 102 may include first and second cooling water supply lines 102 a and 102 b (see FIG. 5) detachably fastened to each other. In this case, the first cooling water supply line 102 a may include a coupling nut 110 a formed at one end, and the second cooling water supply line 102 b may include a male threaded part 112 a formed at one end. Similarly, the cooling water collecting passage 104 may include first and second cooling water collecting lines 104 a and 104 b detachably fastened to each other. In this case, the first cooling water collecting line 104 a may include a coupling nut 110 b formed at one end, and the second cooling water collecting line 104 b may include a male threaded part 112 b formed at one end.

Meanwhile, referring to FIG. 6, in an alternative embodiment, the second conductors 90 b may be cooled using an air cooler. In this case, a plurality of heat radiation fins 114 may be disposed adjacent to the second conductors 90 b.

Referring again to FIGS. 2 to 5, an upper cover 116 a may be installed over the auxiliary coolant reservoir 86. An insulator 118 a may be interposed between the upper cover 116 a and the auxiliary coolant reservoir 86. In addition, a lower cover 116 b may be installed under the cooling water circulation passage 98. In this case, an insulator 118 b may be interposed between the cooling water circulation passage 98 and the lower cover 116 b.

The main chiller 30 of the cooling apparatus in accordance with the present embodiment will now be described in detail. Referring to FIG. 7, the main chiller 30 may employ a mechanical cooler.

Specifically, the main chiller 30 may include a first heat exchanger 120 disposed adjacent to the main coolant reservoir 58. The first heat exchanger 120 may include a cooling cavity 122. In this case, the cooling cavity 122 may be provided through the main coolant reservoir 58. The cooling cavity 122 may be filled with a cooling medium. The cooling medium may be Freon gas, for example. A cooling medium supply passage 124 a and a cooling medium collecting passage 124 b may extend from ends of the cooling cavity 122. A second heat exchanger 126 may be spaced apart from the first heat exchanger 120. In addition, the first heat exchanger 120 may be in communication with the second heat exchanger 126 through the cooling medium supply passage 124 a and the cooling medium collecting passage 124 b. In this case, the cooling medium supply passage 124 a and the cooling medium collecting passage 124 b may be filled with a cooling medium. The second heat exchanger 126 may include a cooling medium cavity 128. The cooling medium cavity 128 may be filled with a cooling medium. In this case, the cooling medium supply passage 124 a may be connected to a first end of the cooling medium cavity 128. Similarly, the cooling medium collecting passage 124 b may be connected to a second end of the cooling medium cavity 128 opposite the first end.

In addition, expansion valves 130 and a pump 132 may be sequentially installed on the cooling medium supply passage 124 a. Further, a compressor 134 may be installed on the cooling medium collecting passage 124 b. Therefore, the cooling medium discharged from the cooling cavity 122 of the first heat exchanger 120 to the cooling medium collecting passage 124 b may be compressed by the compressor 134. The compressed cooling medium may be introduced to the cooling medium cavity 128 of the second heat exchanger 126 for heat-exchange. The second heat exchanger 126 may function as a condenser. In this way, the cooling medium introduced to the cooling medium cavity 128 of the second heat exchanger 126 can be condensed.

The condensed cooling medium may be expanded by the expansion valves 130 to have a low temperature. And the low temperature cooling medium may be introduced to the cooling cavity 122 of the first heat exchanger 120 to cool the coolant in the main coolant reservoir 58. As described above, the cooling medium can circulate by sequentially passing through the compressor 134, the second heat exchanger 126, the expansion valves 130, and the first heat exchanger 120.

Meanwhile, a cooling reservoir 136 may be disposed adjacent to the cooling medium cavity 128 of the second heat exchanger 126. The cooling reservoir 136 may be in communication with a cooling water supply reservoir 140 through a cooling water supply passage 138 a and a cooling water collecting passage 138 b connected to ends thereof, respectively. The cooling water supply reservoir 140 may be filled with cooling water. In addition, a pump 142 may be installed along the cooling water supply passage 138 a. In this way, the cooling water in the cooling water supply reservoir 140 may be pumped by the pump 142 to the cooling reservoir 136 of the second heat exchanger 126 through the cooling water supply passage 138 a. The cooling water supplied to the cooling reservoir 136 may cool the cooling medium in the cooling medium cavity 128 adjacent to the cooling reservoir 136. Therefore, the cooling water, which cooled the cooling medium, may be collected to the cooling water supply reservoir 140 through the cooling water collecting passage 138 b. That is, the cooling water can circulate by sequentially passing through the cooling water supply reservoir 140, the cooling water supply passage 138 a, the cooling reservoir 136, and the cooling water collecting passage 138 b.

In addition, referring to FIG. 8, the main chiller 30 may employ the thermo-electric cooler. More particularly, upper and lower conductors 150 a and 150 b may be disposed adjacent to the main coolant reservoir 58. Semiconductors 152 a and 152 b having different conductivity types may be alternately and repeatedly disposed between the upper and lower conductors 150 a and 150 b. In addition, the semiconductors 152 a and 152 b may be electrically connected to the upper and lower conductors 150 a and 150 b to be electrically connected to each other serially. In this case, when a voltage is applied to the lower conductors 150 b from the power source 154 electrically connected to the lower conductors 150 b, the Peltier Effect occurs. Therefore, the upper conductors 150 a may function as heat absorption plates, and the lower conductors 150 b may function as heat radiation plates. As a result, the upper conductors 150 a heat-exchange with the coolant in the main coolant reservoir 58, thereby cooling the coolant.

In addition, a cooling water circulation passage 156 may be disposed adjacent to the lower conductors 150 b to cool the lower conductors 150 b. Further, an electrical insulating heat conductor 158 a may be disposed between the upper conductors 150 a and the main coolant reservoir 58. Similarly, an electrical insulating heat conductor 158 b may be disposed between the lower conductors 150 b and the cooling water circulation passage 156.

A method of cooling a wafer chuck or a process chamber used for fabricating a semiconductor device in accordance with another aspect of the present invention will now be described.

Referring to FIGS. 2 and 9, a temperature T1 of a coolant is set in the controller 76 (S10). A semiconductor device fabrication process is performed (S20). In this case, a wafer chuck 32 is disposed in a process chamber 34. The wafer chuck 32 may fix a wafer mounted to its surface within the process chamber 34. A process gas is injected into the process chamber 34 to generate plasma in the process chamber 34.

A main chiller 30 filled with the coolant operates (S30). The coolant in the main chiller 30 is cooled by operating the main chiller 30 (S40). The coolant cooled by the main chiller 30 is then supplied to a cooling cavity 56 of the wafer chuck 32 (S50).

A temperature T2 of the coolant supplied to the wafer chuck 32 is measured (S60). The measured temperature T2 of the coolant is compared with the set temperature T1 of the coolant (S70). When the measured temperature T2 is higher than the set temperature T1, the supply of the coolant cooled by the main chiller 30 into the wafer chuck 32 is stopped (S80). At the same time, an auxiliary chiller 84 detachably installed at the main chiller 30 begins to operate. That is, valves 80 a and 80 b disposed on passages 78 a and 78 b in communication with the main chiller 30 and the auxiliary chiller 84 are opened. Next, the coolant cooled by the main chiller 30 is supplied to the auxiliary chiller 84 (S90). The coolant supplied to the auxiliary chiller 84 is additionally cooled by operating the auxiliary chiller 84 (S100 and S110). In one embodiment, a voltage corresponding to a difference between the measured temperature T2 and the set temperature T1 may be applied to the auxiliary chiller 84 so that the additionally cooled coolant can have the set temperature T1. The additionally cooled coolant is thus supplied to the cooling cavity 56 of the wafer chuck 32 (S120). As a result, the wafer chuck 32 can be cooled by the additionally cooled coolant (S130).

As can be seen from the foregoing, a main chiller 30 and an auxiliary chiller 84 detachably installed at the main chiller 30 can be provided so that a coolant cooled by the main chiller will generally be supplied to a wafer chuck, with the auxiliary chiller 84 operating when the coolant needs to be additionally cooled. The auxiliary chiller 84 thereby additionally cools the coolant cooled in the main chiller when necessary. By supplying the additionally cooled coolant to the wafer chuck, it is possible to uniformly maintain the temperature of the wafer chuck even when there is a fluctuation in the temperature of the wafer chuck. In addition, when the cooling capacity of the auxiliary chiller is determined by a voltage applied to the auxiliary chiller corresponding to a desired temperature, it is possible to finely and precisely adjust the amount of the additional cooling.

Exemplary embodiments have been disclosed herein and, although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims. 

1. A cooling apparatus for use in a semiconductor device manufacturing process, said cooling apparatus comprising: a wafer chuck on which a wafer is mounted, the wafer chuck having a cooling cavity formed therein; a main chiller having a main coolant reservoir, the main chiller spaced apart from the wafer chuck; coolant passages for communicating coolant between the cooling cavity and the main coolant reservoir; and an auxiliary chiller detachably installed in communication with one or more of the coolant passages.
 2. The cooling apparatus according to claim 1, wherein the coolant passages comprise a first coolant supply line and a first coolant collecting line connected to the auxiliary chiller.
 3. The cooling apparatus according to claim 2, further comprising: first and second coupling parts disposed on the first coolant supply line connected to the auxiliary chiller, wherein the first and second coupling parts include coupling lines connected to the first coolant supply line, a first switching valve and coupling nuts installed on the coupling lines; and a second switching valve installed along the first coolant supply line and disposed between the first and second coupling parts.
 4. The cooling apparatus according to claim 3, further comprising: a temperature sensor adapted to sense a temperature of the cooling cavity; and a controller electrically connected to the temperature sensor, and the first and second switching valves, wherein the controller operates the first and second switching valves in response to a temperature value transmitted to the controller from the temperature sensor.
 5. The cooling apparatus according to claim 3, wherein the auxiliary chiller comprises: an auxiliary coolant reservoir; second auxiliary coolant supply lines connected to the first and second coupling parts and extending from the auxiliary coolant reservoir; first conductors disposed adjacent to the auxiliary coolant reservoir; second conductors spaced apart from the first conductors; semiconductors disposed between the first and second conductors and electrically connecting the first and second conductors; and a first power source applied to the second conductors.
 6. The cooling apparatus according to claim 5, further comprising: a cooling water circulation passage disposed adjacent to the second conductors; and a cooling water supply reservoir in communication with the cooling water circulation passage.
 7. The cooling apparatus according to claim 5, further comprising heat radiation fins disposed adjacent to the second conductors.
 8. The cooling apparatus according to claim 2, further comprising a coolant heater installed on the first coolant collecting line.
 9. The cooling apparatus according to claim 1, wherein the main chiller comprises: a first heat exchanger disposed adjacent to the main coolant reservoir; first and second cooling medium passages connected to the first heat exchanger; a second heat exchanger in communication with the first heat exchanger through the first and second cooling medium passages; a compressor installed along the first cooling medium passage between the first and second heat exchangers; and expansion valves disposed along the second cooling medium passage between the first and second heat exchangers.
 10. The cooling apparatus according to claim 1, wherein the main chiller comprises: first conductors disposed adjacent to the main coolant reservoir; second conductors spaced apart from the first conductors; semiconductors disposed between the first and second conductors and electrically connecting the first and second conductors; and a power source applied to the second conductors.
 11. An apparatus for fabricating a semiconductor device, comprising: a main chiller; a process chamber; a process gas introduction port in communication with the process chamber; a wafer chuck disposed in the process chamber, the wafer chuck including a cooling cavity formed therein; a coolant supply line connecting the cooling cavity and the main chiller; a coolant collecting line connecting the cooling cavity and the main chiller; an auxiliary chiller detachably installed on the coolant supply line; a process gas exhaust port in communication with the process chamber; and a first power source electrically connected to the process chamber.
 12. The apparatus according to claim 11, further comprising: first and second coupling parts included along the coolant supply line, wherein the first and second coupling parts are connected to the auxiliary chiller; and a first switching valve arranged along the coolant supply line and disposed between the first and second coupling parts.
 13. The apparatus according to claim 12, wherein the first and second coupling parts comprise: coupling lines connected to the coolant supply line; and second switching valves and coupling nuts that are installed along the coupling lines.
 14. The apparatus according to claim 13, further comprising: a temperature sensor that senses a temperature of the cooling cavity; and a controller electrically connected to the temperature sensor and to the first and second switching valves, wherein the controller operates the first and second switching valves in response to the temperature sensed by the temperature sensor.
 15. The apparatus according to claim 12, wherein the auxiliary chiller comprises an auxiliary coolant cavity connected to the first and second coupling parts; first conductors disposed adjacent to the auxiliary coolant cavity; second conductors spaced apart from the first conductors; first semiconductors disposed between the first and second conductors and electrically connecting the first and second conductors; and a second power source connected to the second conductors.
 16. The apparatus according to claim 15, further comprising: a cooling water circulation passage disposed adjacent to the second conductors; and a cooling water supply reservoir arranged in communication with the cooling water circulation passage.
 17. The apparatus according to claim 15, further comprising heat radiation fins disposed adjacent to the second conductors.
 18. The apparatus according to claim 12, further comprising a coolant heater installed along the coolant collecting line.
 19. The apparatus according to claim 11, wherein the main chiller comprises: a main coolant reservoir connected to the coolant supply line and the coolant collecting line; a first heat exchanger disposed adjacent to the main coolant reservoir; first and second cooling medium passages connected to the first heat exchanger; a second heat exchanger in communication with the first heat exchanger through the first and second cooling medium passages; a compressor included in the first cooling medium passage between the first and second heat exchangers; and expansion valves included in the second cooling medium passage between the first and second heat exchangers.
 20. The apparatus according to claim 19, wherein the main chiller further comprises: a second coolant reservoir connected to the coolant supply line and the coolant collecting line; first conductors disposed adjacent to the second coolant reservoir; second conductors spaced apart from the first conductors; semiconductors disposed between the first and second conductors and electrically connecting the first and second conductors; and a second power source applied to the second conductors.
 21. A method of cooling a wafer chuck during a manufacturing process for a semiconductor device, the method comprising: setting a control temperature for a coolant; cooling the coolant in a main chiller; supplying the coolant cooled in the main chiller to a wafer chuck; measuring a temperature of the coolant supplied to the wafer chuck; comparing the measured temperature of the coolant with the control temperature; stopping supply of the cooled coolant to the wafer chuck from the main chiller when the measured temperature is higher than the set temperature; supplying the coolant cooled by the main chiller into an auxiliary chiller; additionally cooling the coolant supplied into the auxiliary chiller; and supplying the additionally cooled coolant from the auxiliary chiller to the wafer chuck.
 22. The method according to claim 21, further comprising: collecting the coolant supplied to the wafer chuck before cooling the coolant in the main chiller; and heating the collected coolant.
 23. The method according to claim 21, wherein the coolant supplied into the auxiliary chiller is additionally cooled by a thermo-electric cooler.
 24. The method according to claim 21, wherein the coolant in the main chiller is cooled by a mechanical cooler including a compressor for compressing a cooling medium, a condenser for condensing the compressed cooling medium, an expansion valve for expanding the condensed cooling medium, and an evaporator for evaporating the expanded cooling medium. 